• Journal of Advanced Marine Engineering and Technology
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• v.40 no.10
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• pp.888-893
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• 2016

In this study, the solution plasma process was utilized with the aim of degrading synthetic dyes in water at atmospheric pressure. The experiments were conducted in a batch-type reactor consisting of a symmetric wire-wire electrode configuration with rhodamine B (RhB) as the target synthetic dye. The effects of the plasma treatment time and initial dye concentration on the RhB degradation were investigated by monitoring the change in absorbance of RhB solutions. The RhB solutions turned lighter in color and finally colorless with prolonged plasma treatment time, indicating the destruction of dye molecules. The RhB solutions were found to have degraded, following the first-order kinetic process. However, for high initial RhB concentrations, another kinetic process or factor seems to play a dominant role at the initial degradation stage. The fitted first-order rate constant decreased as the initial concentration increased. This result suggests that the degradation behavior and kinetic process of the RhB solution strongly depends on its initial concentration. The RhB degradation is considered to be due to a combination of factors, including the formation of chemically oxidative species, as well as the emission of intense UV radiation and high-energy electrons from the plasma. We believe that the solution plasma process may prove to be an effective and environment-friendly method for the degradation or remediation of synthetic dye in wastewater.

• Textile Coloration and Finishing
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• v.33 no.4
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• pp.202-209
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• 2021

Natural dyes are more expensive than synthetic dyes and the dyeing process, which is mainly immersion of dye, is complicated. For this reason, relatively small-scale production methods were predominant. However, awareness and interest in environmental sustainability is rising globally, and the use of synthetic dyes causes various environmental problems such as wastewater and CO₂ emission, so the consumption of natural dyes is increasing. In addition, interest in digital textile printing, an eco-friendly dyeing method that can produce products of various designs and uses less water, is growing. In this study, natural indigo dye (Indigofera tinctoria) was used as a raw material for Digital Textile Printing ink, and ¹⁴C (Biocarbon) present in it was measured to confirm whether it was derived from natural ingredients. The performance was confirmed by testing the pH, viscosity, electrical conductivity, surface tension, and particle size analysis of natural indigo ink. In addition, the performance of natural indigo DTP ink and printing fabric was evaluated by inspecting the change in color fastness and corresponding index substances before and after digital printing with natural indigo DTP ink on textiles. Through this, the possibility of commercialization of DTP ink and printing fabric using natural indigo was confirmed.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1520-1521
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• 2008

There are several ways to demonstrate white organic light emitting diodes (OLEDs) for displays and solid state lighting applications. Among these approaches are the stacked three primary or two complementary colors light-emitting layers, multiple-doped emissive layer, and excimer and exciplex emission [1-10]. We report on white phosphorescent excimer devices by using two light emitting materials based on platinum complexes. These devices showed a peak EQE of 15.7%, with an EQE of 14.5% (17 lm/W) at $500\;cd/m^2$, and a noticeable improvement in both the CIE coordinates (0.381, 0.401) and CRI (81). Devices with the structure ITO/PEDOT:PSS/TCTA (30 nm)/26 mCPy: 12% FPt (10 nm) /26 mCPy: 2% Pt-4 (15 nm)/BCP (40 nm)/CsF/Al [device 1], ITO/PEDOT:PSS/TCTA (30 nm)/26 mCPy: 2% Pt-4 (15 nm)/26 mCPy: 12% FPt (10 nm)/BCP (40 nm)/CsF/Al [device 2], and ITO/PEDOT:PSS/TCTA (30 nm)/26 mCPy: 2% Pt-4: 12% FPt (25 nm)/BCP (40 nm)/CsF/Al [device 3] were fabricated. In these cases, the emissive layer was either the double-layer of 26 mCPy:12% FPt and 15 nm 26 mCPy: 2% Pt-4, or the single layer of 26mCPy with simultaneous doping of Pt-4 and FPt. Device characterization indicates that the CIE coordinates/CRI of device 2 were (0.341, 0.394)/75, (0.295, 0.365)/70 at 5 V and 7 V, respectively. Significant change in EL spectra with the drive voltage was observed for device 2 indicating a shift in the carrier recombination zone, while relatively stable EL spectra was observed for device 1. This indicates a better charge trapping in Pt-4 doped layers [10]. On the other hand, device 3 having a single light-emitting layer (doped simultaneously) emitted a board spectrum combining emission from the Pt-4 monomer and FPt excimer. Moreover, excellent color stability independent of the drive voltage was observed in this case. The CIE coordinates/CRI at 4 V ($40\;cd/m^2$) and 7 V ($7100\;cd/m^2$) were (0.441, 0.421)/83 and (0.440, 0.427)/81, respectively. A balance in the EL spectra can be further obtained by lowering the doping ratio of FPt. In this regard, devices with FPt concentration of 8% (denoted as device 4) were fabricated and characterized. A shift in the CIE coordinates of device 4 from (0.441, 0.421) to (0.382, 0.401) was observed due to an increase in the emission intensity ratio of Pt-4 monomer to FPt excimer. It is worth noting that the CRI values remained above 80 for such device structure. Moreover, a noticeable stability in the EL spectra with respect to changing bias voltage was measured indicating a uniform region for exciton formation. A summary of device characteristics for all cases discussed above is shown in table 1. The forward light output in each case is approximately $500\;cd/m^2$. Other parameters listed are driving voltage (Bias), current density (J), external quantum efficiency (EQE), power efficiency (P.E.), luminous efficiency (cd/A), and CIE coordinates. To conclude, a highly efficient white phosphorescent excimer-based OLEDs made with two light-emitting platinum complexes and having a simple structure showed improved EL characteristics and color properties. The EQE of these devices at $500\;cd/m^2$ is 14.5% with a corresponding power efficiency of 17 lm/W, CIE coordinates of (0.382, 0.401), and CRI of 81.

• Journal of The Korean Astronomical Society
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• v.47 no.5
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• pp.167-178
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• 2014

We search for misclassified type 1 AGNs among type 2 AGNs identified with emission line flux ratios, and investigate the properties of the sample. Using 4 113 local type 2 AGNs at 0.02 < z < 0.05 selected from Sloan Digital Sky Survey Data Release 7, we detected a broad component of the $H{\alpha}$ line with a Full-Width at Half-Maximum (FWHM) ranging from 1 700 to $19090km\;s^{-1}$ for 142 objects, based on the spectral decomposition and visual inspection. The fraction of the misclassified type 1 AGNs among type 2 AGN sample is ~3.5%, implying that a large number of missing type 1 AGN population may exist. The misclassified type 1 AGNs have relatively low luminosity with a mean broad $H{\alpha}$ luminosity, log $L_{H\alpha}=40.50{\pm}0.35\;erg\;s^{-1}$, while black hole mass of the sample is comparable to that of the local black hole population, with a mean black hole mass, log $M_{BH}=6.94{\pm}0.51\;M_{\odot}$. The mean Eddington ratio of the sample is log $L_{bol}/L_{Edd}=-2.00{\pm}0.40$, indicating that black hole activity is relatively weak, hence, AGN continuum is too weak to change the host galaxy color. We find that the O III lines show significant velocity offsets, presumably due to outflows in the narrow-line region, while the velocity offset of the narrow component of the $H{\alpha}$ line is not prominent, consistent with the ionized gas kinematics of general type 1 AGN population.

• Resources Recycling
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• v.20 no.1
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• pp.54-60
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• 2011

The spherical artificial aggregates (AAs) with a diameter of 8 mm, which contains fly ashes discharged from the fluidized bed combustion in a thermal power plant and clay were manufactured by direct sintering method at $1050{\sim}1250^{\circ}C$ for 10 minutes. The effect of fly ash contents on the bloating phenomenon in the AAs was analyzed. The AAs containing fly ash of the amount under 50 wt% showed the black-coring and bloating phenomena. The AAs containing fly ash of the amount over 5Owt%, however, the specific gravity was increased and the color of specimens fully changed to black. These color change phenomena were caused from the formation of FeO by the reduction reaction of almost $Fe_2O_3$ component by the excessive reducing atmosphere formed simultaneously with the rapid emission of the gases generated from the high contents of unburned carbon of with increasing the added fly ash amount. Specific gravity was decreased as fly ash contents increased in the case of sintering at the same temperature condition. Water absorption of all specimens except of the specimens containing 10 wt% fly ashes decreased with increasing sintering temperature. These were because a liquid phase was formed as the increasing the sintering temperature. In the case of the specimens manufactured in this study containing fly ashes discharged from the fluidized bed combustor in a the thermal power plant and 10~90 wt% of clay, the specific gravity was 0.9~1.8 and the water absorptivity was 8~60%, therefore it is considered that those results can be applied to the light or heavy aggregates.

• Journal of the Korean Chemical Society
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• v.50 no.3
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• pp.237-242
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• 2006

Nowadays, LEDs has been applied to the luminescent devices of various fields because of the invention of high efficient blue chip. Recently, especially, the white LEDs composed of InGaN blue chips and a yellow phosphor (YAG:Ce3+) have been investigated extensively. With the exception of YAG:Ce3+ phosphor, however, there are no reports on yellow phosphor that has significant emission in the 450~470 nm excitation range and this LED system is the rather low color rendering index due to their using two wavelength. Hence, we have attempted to synthesize thiogallate phosphors that efficiently under the long wavelength excitation range in the present case. Among those phosphors, we have synthesized Sr2Ga2S5:Eu2+ phosphor by change the host material of SrGa2S4:Eu2+ which is well known phosphor and we investigated the luminescent properties. In order to obtain the harmlessness and simplification of the synthesis process, sulfide materials and mixture gas of 5 % H2/95 % N2 were used instead of the CS2 or H2S gas. The prepared phosphor shows the yellow color peaking at the 550 nm wavelength and it possible to emit efficiently under the broad excitation band in the range of 300~500 nm. And this phosphor shows high luminescent intensity more than 110 % in comparison with commercial YAG:Ce3+ phosphor and it can be applied for UV LED due to excitation property in UV region.